commit b5ec5ce0e39d6e7ea707d5604a5f6d567dfd2f48
Author: john cooper <john.cooper@redhat.com>
Date:   Sat Feb 20 11:14:59 2010 -0600

    Add cpu model configuration support..
    
    This is a reimplementation of prior versions which adds
    the ability to define cpu models for contemporary processors.
    The added models are likewise selected via -cpu <name>,
    and are intended to displace the existing convention
    of "-cpu qemu64" augmented with a series of feature flags.
    
    A primary motivation was determination of a least common
    denominator within a given processor class to simplify guest
    migration.  It is still possible to modify an arbitrary model
    via additional feature flags however the goal here was to
    make doing so unnecessary in typical usage.  The other
    consideration was providing models names reflective of
    current processors.  Both AMD and Intel have reviewed the
    models in terms of balancing generality of migration vs.
    excessive feature downgrade relative to released silicon.
    
    This version of the patch replaces the prior hard wired
    definitions with a configuration file approach for new
    models.  Existing models are thus far left as-is but may
    easily be transitioned to (or may be overridden by) the
    configuration file representation.
    
    Proposed new model definitions are provided here for current
    AMD and Intel processors.  Each model consists of a name
    used to select it on the command line (-cpu <name>), and a
    model_id which corresponds to a least common denominator
    commercial instance of the processor class.
    
    A table of names/model_ids may be queried via "-cpu ?model":
    
            :
        x86       Opteron_G3  AMD Opteron 23xx (Gen 3 Class Opteron)
        x86       Opteron_G2  AMD Opteron 22xx (Gen 2 Class Opteron)
        x86       Opteron_G1  AMD Opteron 240 (Gen 1 Class Opteron)
        x86          Nehalem  Intel Core i7 9xx (Nehalem Class Core i7)
        x86           Penryn  Intel Core 2 Duo P9xxx (Penryn Class Core 2)
        x86           Conroe  Intel Celeron_4x0 (Conroe/Merom Class Core 2)
            :
    
    Also added is "-cpu ?dump" which exhaustively outputs all config
    data for all defined models, and "-cpu ?cpuid" which enumerates
    all qemu recognized CPUID feature flags.
    
    The pseudo cpuid flag 'check' when added to the feature flag list
    will warn when feature flags (either implicit in a cpu model or
    explicit on the command line) would have otherwise been quietly
    unavailable to a guest:
    
        # qemu-system-x86_64 ... -cpu Nehalem,check
        warning: host cpuid 0000_0001 lacks requested flag 'sse4.2|sse4_2' [0x00100000]
        warning: host cpuid 0000_0001 lacks requested flag 'popcnt' [0x00800000]
    
    A similar 'enforce' pseudo flag exists which in addition
    to the above causes qemu to error exit if requested flags are
    unavailable.
    
    Configuration data for a cpu model resides in the target config
    file which by default will be installed as:
    
        /usr/local/etc/qemu/target-<arch>.conf
    
    The format of this file should be self explanatory given the
    definitions for the above six models and essentially mimics
    the structure of the static x86_def_t x86_defs.
    
    Encoding of cpuid flags names now allows aliases for both the
    configuration file and the command line which reconciles some
    Intel/AMD/Linux/Qemu naming differences.
    
    This patch was tested relative to qemu.git.
    
    Signed-off-by: john cooper <john.cooper@redhat.com>
    Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/target-i386/helper.c b/target-i386/helper.c
index 70762bb..7cda864 100644
--- a/target-i386/helper.c
+++ b/target-i386/helper.c
@@ -29,33 +29,52 @@
 #include "kvm.h"
 
 //#define DEBUG_MMU
+#include "qemu-option.h"
+#include "qemu-config.h"
 
 /* feature flags taken from "Intel Processor Identification and the CPUID
- * Instruction" and AMD's "CPUID Specification". In cases of disagreement
- * about feature names, the Linux name is used. */
+ * Instruction" and AMD's "CPUID Specification".  In cases of disagreement
+ * between feature naming conventions, aliases may be added.
+ */
 static const char *feature_name[] = {
-    "fpu", "vme", "de", "pse", "tsc", "msr", "pae", "mce",
-    "cx8", "apic", NULL, "sep", "mtrr", "pge", "mca", "cmov",
-    "pat", "pse36", "pn" /* Intel psn */, "clflush" /* Intel clfsh */, NULL, "ds" /* Intel dts */, "acpi", "mmx",
-    "fxsr", "sse", "sse2", "ss", "ht" /* Intel htt */, "tm", "ia64", "pbe",
+    "fpu", "vme", "de", "pse",
+    "tsc", "msr", "pae", "mce",
+    "cx8", "apic", NULL, "sep",
+    "mtrr", "pge", "mca", "cmov",
+    "pat", "pse36", "pn" /* Intel psn */, "clflush" /* Intel clfsh */,
+    NULL, "ds" /* Intel dts */, "acpi", "mmx",
+    "fxsr", "sse", "sse2", "ss",
+    "ht" /* Intel htt */, "tm", "ia64", "pbe",
 };
 static const char *ext_feature_name[] = {
-    "pni" /* Intel,AMD sse3 */, NULL, NULL, "monitor", "ds_cpl", "vmx", NULL /* Linux smx */, "est",
-    "tm2", "ssse3", "cid", NULL, NULL, "cx16", "xtpr", NULL,
-    NULL, NULL, "dca", NULL, NULL, NULL, NULL, "popcnt",
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, "hypervisor",
+    "pni|sse3" /* Intel,AMD sse3 */, NULL, NULL, "monitor",
+    "ds_cpl", "vmx", NULL /* Linux smx */, "est",
+    "tm2", "ssse3", "cid", NULL,
+    NULL, "cx16", "xtpr", NULL,
+    NULL, NULL, "dca", "sse4.1|sse4_1",
+    "sse4.2|sse4_2", "x2apic", NULL, "popcnt",
+    NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, "hypervisor",
 };
 static const char *ext2_feature_name[] = {
-    "fpu", "vme", "de", "pse", "tsc", "msr", "pae", "mce",
-    "cx8" /* AMD CMPXCHG8B */, "apic", NULL, "syscall", "mtrr", "pge", "mca", "cmov",
-    "pat", "pse36", NULL, NULL /* Linux mp */, "nx" /* Intel xd */, NULL, "mmxext", "mmx",
-    "fxsr", "fxsr_opt" /* AMD ffxsr */, "pdpe1gb" /* AMD Page1GB */, "rdtscp", NULL, "lm" /* Intel 64 */, "3dnowext", "3dnow",
+    "fpu", "vme", "de", "pse",
+    "tsc", "msr", "pae", "mce",
+    "cx8" /* AMD CMPXCHG8B */, "apic", NULL, "syscall",
+    "mtrr", "pge", "mca", "cmov",
+    "pat", "pse36", NULL, NULL /* Linux mp */,
+    "nx" /* Intel xd */, NULL, "mmxext", "mmx",
+    "fxsr", "fxsr_opt" /* AMD ffxsr */, "pdpe1gb" /* AMD Page1GB */, "rdtscp",
+    NULL, "lm" /* Intel 64 */, "3dnowext", "3dnow",
 };
 static const char *ext3_feature_name[] = {
-    "lahf_lm" /* AMD LahfSahf */, "cmp_legacy", "svm", "extapic" /* AMD ExtApicSpace */, "cr8legacy" /* AMD AltMovCr8 */, "abm", "sse4a", "misalignsse",
-    "3dnowprefetch", "osvw", NULL /* Linux ibs */, NULL, "skinit", "wdt", NULL, NULL,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+    "lahf_lm" /* AMD LahfSahf */, "cmp_legacy", "svm", "extapic" /* AMD ExtApicSpace */,
+    "cr8legacy" /* AMD AltMovCr8 */, "abm", "sse4a", "misalignsse",
+    "3dnowprefetch", "osvw", NULL /* Linux ibs */, NULL,
+    "skinit", "wdt", NULL, NULL,
+    NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL,
+    NULL, NULL, NULL, NULL,
 };
 
 static const char *kvm_feature_name[] = {
@@ -65,47 +84,99 @@ static const char *kvm_feature_name[] = {
     NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
 };
 
+/* collects per-function cpuid data
+ */
+typedef struct model_features_t {
+    uint32_t *guest_feat;
+    uint32_t *host_feat;
+    uint32_t check_feat;
+    const char **flag_names;
+    uint32_t cpuid;
+    } model_features_t;
+
+int check_cpuid = 0;
+int enforce_cpuid = 0;
+
+static void host_cpuid(uint32_t function, uint32_t count, uint32_t *eax,
+                       uint32_t *ebx, uint32_t *ecx, uint32_t *edx);
+
+#define iswhite(c) ((c) && ((c) <= ' ' || '~' < (c)))
+
+/* general substring compare of *[s1..e1) and *[s2..e2).  sx is start of
+ * a substring.  ex if !NULL points to the first char after a substring,
+ * otherwise the string is assumed to sized by a terminating nul.
+ * Return lexical ordering of *s1:*s2.
+ */
+static int sstrcmp(const char *s1, const char *e1, const char *s2,
+    const char *e2)
+{
+    for (;;) {
+        if (!*s1 || !*s2 || *s1 != *s2)
+            return (*s1 - *s2);
+        ++s1, ++s2;
+        if (s1 == e1 && s2 == e2)
+            return (0);
+        else if (s1 == e1)
+            return (*s2);
+        else if (s2 == e2)
+            return (*s1);
+    }
+}
+
+/* compare *[s..e) to *altstr.  *altstr may be a simple string or multiple
+ * '|' delimited (possibly empty) strings in which case search for a match
+ * within the alternatives proceeds left to right.  Return 0 for success,
+ * non-zero otherwise.
+ */
+static int altcmp(const char *s, const char *e, const char *altstr)
+{
+    const char *p, *q;
+
+    for (q = p = altstr; ; ) {
+        while (*p && *p != '|')
+            ++p;
+        if ((q == p && !*s) || (q != p && !sstrcmp(s, e, q, p)))
+            return (0);
+        if (!*p)
+            return (1);
+        else
+            q = ++p;
+    }
+}
+
+/* search featureset for flag *[s..e), if found set corresponding bit in
+ * *pval and return success, otherwise return zero
+ */
+static int lookup_feature(uint32_t *pval, const char *s, const char *e,
+    const char **featureset)
+{
+    uint32_t mask;
+    const char **ppc;
+
+    for (mask = 1, ppc = featureset; mask; mask <<= 1, ++ppc)
+        if (*ppc && !altcmp(s, e, *ppc)) {
+            *pval |= mask;
+            break;
+        }
+    return (mask ? 1 : 0);
+}
+
 static void add_flagname_to_bitmaps(const char *flagname, uint32_t *features,
                                     uint32_t *ext_features,
                                     uint32_t *ext2_features,
                                     uint32_t *ext3_features,
                                     uint32_t *kvm_features)
 {
-    int i;
-    int found = 0;
-
-    for ( i = 0 ; i < 32 ; i++ )
-        if (feature_name[i] && !strcmp (flagname, feature_name[i])) {
-            *features |= 1 << i;
-            found = 1;
-        }
-    for ( i = 0 ; i < 32 ; i++ )
-        if (ext_feature_name[i] && !strcmp (flagname, ext_feature_name[i])) {
-            *ext_features |= 1 << i;
-            found = 1;
-        }
-    for ( i = 0 ; i < 32 ; i++ )
-        if (ext2_feature_name[i] && !strcmp (flagname, ext2_feature_name[i])) {
-            *ext2_features |= 1 << i;
-            found = 1;
-        }
-    for ( i = 0 ; i < 32 ; i++ )
-        if (ext3_feature_name[i] && !strcmp (flagname, ext3_feature_name[i])) {
-            *ext3_features |= 1 << i;
-            found = 1;
-        }
-    for ( i = 0 ; i < 32 ; i++ )
-        if (kvm_feature_name[i] && !strcmp (flagname, kvm_feature_name[i])) {
-            *kvm_features |= 1 << i;
-            found = 1;
-        }
-
-    if (!found) {
-        fprintf(stderr, "CPU feature %s not found\n", flagname);
-    }
+    if (!lookup_feature(features, flagname, NULL, feature_name) &&
+        !lookup_feature(ext_features, flagname, NULL, ext_feature_name) &&
+        !lookup_feature(ext2_features, flagname, NULL, ext2_feature_name) &&
+        !lookup_feature(ext3_features, flagname, NULL, ext3_feature_name) &&
+        !lookup_feature(kvm_features, flagname, NULL, kvm_feature_name))
+            fprintf(stderr, "CPU feature %s not found\n", flagname);
 }
 
 typedef struct x86_def_t {
+    struct x86_def_t *next;
     const char *name;
     uint32_t level;
     uint32_t vendor1, vendor2, vendor3;
@@ -116,6 +187,7 @@ typedef struct x86_def_t {
     uint32_t xlevel;
     char model_id[48];
     int vendor_override;
+    uint32_t flags;
 } x86_def_t;
 
 #define I486_FEATURES (CPUID_FP87 | CPUID_VME | CPUID_PSE)
@@ -129,7 +201,14 @@ typedef struct x86_def_t {
           CPUID_MSR | CPUID_MCE | CPUID_CX8 | CPUID_PGE | CPUID_CMOV | \
           CPUID_PAT | CPUID_FXSR | CPUID_MMX | CPUID_SSE | CPUID_SSE2 | \
           CPUID_PAE | CPUID_SEP | CPUID_APIC)
-static x86_def_t x86_defs[] = {
+
+/* maintains list of cpu model definitions
+ */
+static x86_def_t *x86_defs = {NULL};
+
+/* built-in cpu model definitions (deprecated)
+ */
+static x86_def_t builtin_x86_defs[] = {
 #ifdef TARGET_X86_64
     {
         .name = "qemu64",
@@ -334,9 +413,6 @@ static x86_def_t x86_defs[] = {
     },
 };
 
-static void host_cpuid(uint32_t function, uint32_t count, uint32_t *eax,
-                               uint32_t *ebx, uint32_t *ecx, uint32_t *edx);
-
 static int cpu_x86_fill_model_id(char *str)
 {
     uint32_t eax = 0, ebx = 0, ecx = 0, edx = 0;
@@ -382,6 +458,51 @@ static int cpu_x86_fill_host(x86_def_t *x86_cpu_def)
     return 0;
 }
 
+static int unavailable_host_feature(struct model_features_t *f, uint32_t mask)
+{
+    int i;
+
+    for (i = 0; i < 32; ++i)
+        if (1 << i & mask) {
+            fprintf(stderr, "warning: host cpuid %04x_%04x lacks requested"
+                " flag '%s' [0x%08x]\n",
+                f->cpuid >> 16, f->cpuid & 0xffff,
+                f->flag_names[i] ? f->flag_names[i] : "[reserved]", mask);
+            break;
+        }
+    return 0;
+}
+
+/* best effort attempt to inform user requested cpu flags aren't making
+ * their way to the guest.  Note: ft[].check_feat ideally should be
+ * specified via a guest_def field to suppress report of extraneous flags.
+ */
+static int check_features_against_host(x86_def_t *guest_def)
+{
+    x86_def_t host_def;
+    uint32_t mask;
+    int rv, i;
+    struct model_features_t ft[] = {
+        {&guest_def->features, &host_def.features,
+            ~0, feature_name, 0x00000000},
+        {&guest_def->ext_features, &host_def.ext_features,
+            ~CPUID_EXT_HYPERVISOR, ext_feature_name, 0x00000001},
+        {&guest_def->ext2_features, &host_def.ext2_features,
+            ~PPRO_FEATURES, ext2_feature_name, 0x80000000},
+        {&guest_def->ext3_features, &host_def.ext3_features,
+            ~CPUID_EXT3_SVM, ext3_feature_name, 0x80000001}};
+
+    cpu_x86_fill_host(&host_def);
+    for (rv = 0, i = 0; i < sizeof (ft) / sizeof (ft[0]); ++i)
+        for (mask = 1; mask; mask <<= 1)
+            if (ft[i].check_feat & mask && *ft[i].guest_feat & mask &&
+                !(*ft[i].host_feat & mask)) {
+                    unavailable_host_feature(&ft[i], mask);
+                    rv = 1;
+                }
+    return rv;
+}
+
 static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *cpu_model)
 {
     unsigned int i;
@@ -393,13 +514,9 @@ static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *cpu_model)
     uint32_t minus_features = 0, minus_ext_features = 0, minus_ext2_features = 0, minus_ext3_features = 0, minus_kvm_features = 0;
     uint32_t numvalue;
 
-    def = NULL;
-    for (i = 0; i < ARRAY_SIZE(x86_defs); i++) {
-        if (strcmp(name, x86_defs[i].name) == 0) {
-            def = &x86_defs[i];
+    for (def = x86_defs; def; def = def->next)
+        if (!strcmp(name, def->name))
             break;
-        }
-    }
     if (kvm_enabled() && strcmp(name, "host") == 0) {
         cpu_x86_fill_host(x86_cpu_def);
     } else if (!def) {
@@ -488,6 +605,10 @@ static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *cpu_model)
                 fprintf(stderr, "unrecognized feature %s\n", featurestr);
                 goto error;
             }
+        } else if (!strcmp(featurestr, "check")) {
+            check_cpuid = 1;
+        } else if (!strcmp(featurestr, "enforce")) {
+            check_cpuid = enforce_cpuid = 1;
         } else {
             fprintf(stderr, "feature string `%s' not in format (+feature|-feature|feature=xyz)\n", featurestr);
             goto error;
@@ -504,6 +625,10 @@ static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *cpu_model)
     x86_cpu_def->ext2_features &= ~minus_ext2_features;
     x86_cpu_def->ext3_features &= ~minus_ext3_features;
     x86_cpu_def->kvm_features &= ~minus_kvm_features;
+    if (check_cpuid) {
+        if (check_features_against_host(x86_cpu_def) && enforce_cpuid)
+            goto error;
+    }
     free(s);
     return 0;
 
@@ -512,12 +637,97 @@ error:
     return -1;
 }
 
-void x86_cpu_list (FILE *f, int (*cpu_fprintf)(FILE *f, const char *fmt, ...))
+/* generate a composite string into buf of all cpuid names in featureset
+ * selected by fbits.  indicate truncation at bufsize in the event of overflow.
+ * if flags, suppress names undefined in featureset.
+ */
+static void listflags(char *buf, int bufsize, uint32_t fbits,
+    const char **featureset, uint32_t flags)
 {
-    unsigned int i;
+    const char **p = &featureset[31];
+    char *q, *b, bit;
+    int nc;
+
+    b = 4 <= bufsize ? buf + (bufsize -= 3) - 1 : NULL;
+    *buf = '\0';
+    for (q = buf, bit = 31; fbits && bufsize; --p, fbits &= ~(1 << bit), --bit)
+        if (fbits & 1 << bit && (*p || !flags)) {
+            if (*p)
+                nc = snprintf(q, bufsize, "%s%s", q == buf ? "" : " ", *p);
+            else
+                nc = snprintf(q, bufsize, "%s[%d]", q == buf ? "" : " ", bit);
+            if (bufsize <= nc) {
+                if (b)
+                    sprintf(b, "...");
+                return;
+            }
+            q += nc;
+            bufsize -= nc;
+        }
+}
 
-    for (i = 0; i < ARRAY_SIZE(x86_defs); i++)
-        (*cpu_fprintf)(f, "x86 %16s\n", x86_defs[i].name);
+/* generate CPU information:
+ * -?        list model names
+ * -?model   list model names/IDs
+ * -?dump    output all model (x86_def_t) data
+ * -?cpuid   list all recognized cpuid flag names
+ */ 
+void x86_cpu_list (FILE *f, int (*cpu_fprintf)(FILE *f, const char *fmt, ...),
+                  const char *optarg)
+{
+    unsigned char model = !strcmp("?model", optarg);
+    unsigned char dump = !strcmp("?dump", optarg);
+    unsigned char cpuid = !strcmp("?cpuid", optarg);
+    x86_def_t *def;
+    char buf[256];
+
+    if (cpuid) {
+        (*cpu_fprintf)(f, "Recognized CPUID flags:\n");
+        listflags(buf, sizeof (buf), (uint32_t)~0, feature_name, 1);
+        (*cpu_fprintf)(f, "  f_edx: %s\n", buf);
+        listflags(buf, sizeof (buf), (uint32_t)~0, ext_feature_name, 1);
+        (*cpu_fprintf)(f, "  f_ecx: %s\n", buf);
+        listflags(buf, sizeof (buf), (uint32_t)~0, ext2_feature_name, 1);
+        (*cpu_fprintf)(f, "  extf_edx: %s\n", buf);
+        listflags(buf, sizeof (buf), (uint32_t)~0, ext3_feature_name, 1);
+        (*cpu_fprintf)(f, "  extf_ecx: %s\n", buf);
+        return;
+    }
+    for (def = x86_defs; def; def = def->next) {
+        snprintf(buf, sizeof (buf), def->flags ? "[%s]": "%s", def->name);
+        if (model || dump) {
+            (*cpu_fprintf)(f, "x86 %16s  %-48s\n", buf, def->model_id);
+        } else {
+            (*cpu_fprintf)(f, "x86 %16s\n", buf);
+        }
+        if (dump) {
+            memcpy(buf, &def->vendor1, sizeof (def->vendor1));
+            memcpy(buf + 4, &def->vendor2, sizeof (def->vendor2));
+            memcpy(buf + 8, &def->vendor3, sizeof (def->vendor3));
+            buf[12] = '\0';
+            (*cpu_fprintf)(f,
+                "  family %d model %d stepping %d level %d xlevel 0x%x"
+                " vendor \"%s\"\n",
+                def->family, def->model, def->stepping, def->level,
+                def->xlevel, buf);
+            listflags(buf, sizeof (buf), def->features, feature_name, 0);
+            (*cpu_fprintf)(f, "  feature_edx %08x (%s)\n", def->features,
+                buf);
+            listflags(buf, sizeof (buf), def->ext_features, ext_feature_name,
+                0);
+            (*cpu_fprintf)(f, "  feature_ecx %08x (%s)\n", def->ext_features,
+                buf);
+            listflags(buf, sizeof (buf), def->ext2_features, ext2_feature_name,
+                0);
+            (*cpu_fprintf)(f, "  extfeature_edx %08x (%s)\n",
+                def->ext2_features, buf);
+            listflags(buf, sizeof (buf), def->ext3_features, ext3_feature_name,
+                0);
+            (*cpu_fprintf)(f, "  extfeature_ecx %08x (%s)\n",
+                def->ext3_features, buf);
+            (*cpu_fprintf)(f, "\n");
+        }
+    }
 }
 
 static int cpu_x86_register (CPUX86State *env, const char *cpu_model)
@@ -566,6 +776,128 @@ static int cpu_x86_register (CPUX86State *env, const char *cpu_model)
     return 0;
 }
 
+#if !defined(CONFIG_LINUX_USER)
+/* copy vendor id string to 32 bit register, nul pad as needed
+ */
+static void cpyid(const char *s, uint32_t *id)
+{
+    char *d = (char *)id;
+    char i;
+
+    for (i = sizeof (*id); i--; )
+        *d++ = *s ? *s++ : '\0';
+}
+
+/* interpret radix and convert from string to arbitrary scalar,
+ * otherwise flag failure
+ */
+#define setscalar(pval, str, perr)                      \
+{                                                       \
+    char *pend;                                         \
+    unsigned long ul;                                   \
+                                                        \
+    ul = strtoul(str, &pend, 0);                        \
+    *str && !*pend ? (*pval = ul) : (*perr = 1);        \
+}
+
+/* map cpuid options to feature bits, otherwise return failure
+ * (option tags in *str are delimited by whitespace)
+ */
+static void setfeatures(uint32_t *pval, const char *str,
+    const char **featureset, int *perr)
+{
+    const char *p, *q;
+
+    for (q = p = str; *p || *q; q = p) {
+        while (iswhite(*p))
+            q = ++p; 
+        while (*p && !iswhite(*p))
+            ++p;
+        if (!*q && !*p)
+            return;
+        if (!lookup_feature(pval, q, p, featureset)) {
+            fprintf(stderr, "error: feature \"%.*s\" not available in set\n",
+                (int)(p - q), q);
+            *perr = 1;
+            return;
+        }
+    }
+}
+
+/* map config file options to x86_def_t form
+ */
+static int cpudef_setfield(const char *name, const char *str, void *opaque)
+{
+    x86_def_t *def = opaque;
+    int err = 0;
+
+    if (!strcmp(name, "name")) {
+        def->name = strdup(str);
+    } else if (!strcmp(name, "model_id")) {
+        strncpy(def->model_id, str, sizeof (def->model_id));
+    } else if (!strcmp(name, "level")) {
+        setscalar(&def->level, str, &err)
+    } else if (!strcmp(name, "vendor")) {
+        cpyid(&str[0], &def->vendor1);
+        cpyid(&str[4], &def->vendor2);
+        cpyid(&str[8], &def->vendor3);
+    } else if (!strcmp(name, "family")) {
+        setscalar(&def->family, str, &err)
+    } else if (!strcmp(name, "model")) {
+        setscalar(&def->model, str, &err)
+    } else if (!strcmp(name, "stepping")) {
+        setscalar(&def->stepping, str, &err)
+    } else if (!strcmp(name, "feature_edx")) {
+        setfeatures(&def->features, str, feature_name, &err);
+    } else if (!strcmp(name, "feature_ecx")) {
+        setfeatures(&def->ext_features, str, ext_feature_name, &err);
+    } else if (!strcmp(name, "extfeature_edx")) {
+        setfeatures(&def->ext2_features, str, ext2_feature_name, &err);
+    } else if (!strcmp(name, "extfeature_ecx")) {
+        setfeatures(&def->ext3_features, str, ext3_feature_name, &err);
+    } else if (!strcmp(name, "xlevel")) {
+        setscalar(&def->xlevel, str, &err)
+    } else {
+        fprintf(stderr, "error: unknown option [%s = %s]\n", name, str);
+        return (1);
+    }
+    if (err) {
+        fprintf(stderr, "error: bad option value [%s = %s]\n", name, str);
+        return (1);
+    }
+    return (0);
+}
+
+/* register config file entry as x86_def_t
+ */
+static int cpudef_register(QemuOpts *opts, void *opaque)
+{
+    x86_def_t *def = qemu_mallocz(sizeof (x86_def_t));
+
+    qemu_opt_foreach(opts, cpudef_setfield, def, 1);
+    def->next = x86_defs;
+    x86_defs = def;
+    return (0);
+}
+#endif	/* !CONFIG_LINUX_USER */
+
+/* register "cpudef" models defined in configuration file.  Here we first
+ * preload any built-in definitions
+ */
+void x86_cpudef_setup(void)
+{
+    int i;
+
+    for (i = 0; i < ARRAY_SIZE(builtin_x86_defs); ++i) {
+        builtin_x86_defs[i].next = x86_defs;
+        builtin_x86_defs[i].flags = 1;
+        x86_defs = &builtin_x86_defs[i];
+    }
+#if !defined(CONFIG_LINUX_USER)
+    qemu_opts_foreach(&qemu_cpudef_opts, cpudef_register, NULL, 0);
+#endif
+}
+
 /* NOTE: must be called outside the CPU execute loop */
 void cpu_reset(CPUX86State *env)
 {
